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FAQ (Frequently Asked Questions)

Q1: I would like to buy this Navien heater to replace another water heater that uses metal vent pipe. I read the manual that describes various PVC products to use for venting. The manual does not state that metal should not be used. Are there any performance issues if I use my metal exhaust vent pipe and not the PVC type pipe?

A1: Yes, the reason for using PVC versus metal is for energy efficiency. Navien recommends using PVC because the NPE and NR heaters are condensing type heaters. Using PVC provides the maximum condensing function. The Navien heaters will run more efficiently with PVC.

Yes, you could use your metal venting instead of PVC; the heater will still work safely. Alternatively, you could install the PVC inside the metal venting, using the metal venting as a chase (like a conduit).

Q2: What are the differences between the NPE series and the NR series heaters?

A2:* Efficiency is slightly higher on the NPE.* NPE has a front panel display where you can change the temperature as well as see diagnostic messages. On the NR, temperature changes can only be done with the remote control or inside the unit.* The gas valve on the NPE is negative pressure. On the NR it is positive pressure, which relies on the pressure of the gas line.* The gas connection on NPE is on the left. On the NR it is on the right.* NR has 3" exhaust and intake venting. The NPE has 2" exhaust and intake venting. Conversion from 3" to 2" can be done with a common 3" to 2" reducer here http://gadgetsgo.com/Charlotte-Pipe-3-2-PVC-DWV-Coupling-PDWVRMK-PVC00102.html. Both the NR and NPE use Schedule 40 PVC.* NR dimensions: 17.0 W x 28.0 H 14" D* NPE dimensions: 17.3 W x 27.4" H 11.4" D* The NPE series has many more improvements over the NR series.

Installation Help and Recommendations

We recommend that you have a professional tankless water heater installer review the above recommendations. Improper installation may cause loss of life and/or property.